Recently, a high-frequency bias supply circuit having a plurality of quarter-wave lines has been used for a transmitter, etc. in a radio communication system, such as a satellite communication system, a telephone communication system, etc. in order to increase a level of current without affecting a RF (radio frequency) signal to be transmitted.
According to a conventional high-frequency bias supply circuit, however, there is a disadvantage in that available frequency bandwidth is not expanded sufficiently, because a ripple occurs in a signal-loss characteristic in the frequency bandwidth.